/*
 * Copyright 2012-2014 the original author or authors.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package org.springframework.boot.bind;

import java.util.Collections;
import java.util.LinkedHashMap;
import java.util.Map;

import org.springframework.core.env.EnumerablePropertySource;
import org.springframework.core.env.PropertySource;
import org.springframework.core.env.PropertySources;

/**
 * Convenience class for manipulating PropertySources.
 *
 * @author Dave Syer
 *
 * @see PropertySource
 * @see PropertySources
 */
public abstract class PropertySourceUtils {

	/**
	 * Return a Map of all values from the specified {@link PropertySources} that start
	 * with a particular key.
	 * @param propertySources the property sources to scan
	 * @param keyPrefix the key prefixes to test
	 * @return a map of all sub properties starting with the specified key prefixes.
	 * @see PropertySourceUtils#getSubProperties(PropertySources, String, String)
	 */
	public static Map<String, Object> getSubProperties(PropertySources propertySources,
			String keyPrefix) {
		return PropertySourceUtils.getSubProperties(propertySources, null, keyPrefix);
	}

	/**
	 * Return a Map of all values from the specified {@link PropertySources} that start
	 * with a particular key.
	 * @param propertySources the property sources to scan
	 * @param rootPrefix a root prefix to be prepended to the keyPrefix (can be
	 * {@code null})
	 * @param keyPrefix the key prefixes to test
	 * @return a map of all sub properties starting with the specified key prefixes.
	 * @see #getSubProperties(PropertySources, String, String)
	 */
	public static Map<String, Object> getSubProperties(PropertySources propertySources,
			String rootPrefix, String keyPrefix) {
		RelaxedNames keyPrefixes = new RelaxedNames(keyPrefix);
		Map<String, Object> subProperties = new LinkedHashMap<String, Object>();
		for (PropertySource<?> source : propertySources) {
			if (source instanceof EnumerablePropertySource) {
				for (String name : ((EnumerablePropertySource<?>) source)
						.getPropertyNames()) {
					String key = PropertySourceUtils.getSubKey(name, rootPrefix,
							keyPrefixes);
					if (key != null && !subProperties.containsKey(key)) {
						subProperties.put(key, source.getProperty(name));
					}
				}
			}
		}
		return Collections.unmodifiableMap(subProperties);
	}

	private static String getSubKey(String name, String rootPrefixes,
			RelaxedNames keyPrefix) {
		rootPrefixes = (rootPrefixes == null ? "" : rootPrefixes);
		for (String rootPrefix : new RelaxedNames(rootPrefixes)) {
			for (String candidateKeyPrefix : keyPrefix) {
				if (name.startsWith(rootPrefix + candidateKeyPrefix)) {
					return name.substring((rootPrefix + candidateKeyPrefix).length());
				}
			}
		}
		return null;
	}

}
